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Allen Bradley PLC 5 1785-BCM

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1785-BCM

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The Allen-Bradley 1785-BCM is a Backup Communications Module (BCM) that is used to provide high-speed switchover of communication path using Data Highway Plus (DH+) and Remote I/O (RIO) protocol. It is used for redundant PLC5 processor configuration and compatible for use with PLC5 processors such as PLC-5/15 series B, -5/20, -5/25, -5/30, -5/40, and -5/60 processors.

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Rockwell Disclaimer: The product is used surplus. DO Supply is not an authorized surplus dealer or affiliate for the Manufacturer of this product. The product may have older date codes or be an older series than that available direct from the factory or authorized dealers. Because DO Supply is not an authorized distributor of this product, the Original Manufacturer's warranty does not apply. While many Allen-Bradley PLC products will have firmware already installed, DO Supply makes no representation as to whether a PLC product will or will not have firmware and, if it does have firmware, whether the firmware is the revision level that you need for your application. DO Supply also makes no representations as to your ability or right to download or otherwise obtain firmware for the product from Rockwell, its distributors, or any other source. DO Supply also makes no representations as to your right to install any such firmware on the product. DO Supply will not obtain or supply firmware on your behalf. It is your obligation to comply with the terms of any End-User License Agreement or similar document related to obtaining or installing firmware.

Technical specifications for 1785-BCM

ManufacturerAllen Bradley
CategoryPLCs
Product LinePLC 5
Part Number1785-BCM
Weight1.31 lbs (0.60 kg)
Wiring Arm1771-WG
DH+/RIO Interface2
High Speed Serial Link Interface1
Module TypeBackup Communications Module
Compatible processorsPLC-5/15 series B, -5/20, -5/25, -5/30, -5/40, and -5/60
Module Location1771 I/O Chassis (local)
Keying Locationsbetween 8 and 10 between 34 and 36
Customer Relay.25A @ 24V dc (resistive)
HSSLcommunicates with 1.2 Megabaud
Operational Temperature0 Deg. Celsius to 60 Deg. Celsius (32 Deg. Fahrenheit to 140 Degree Fahrenheit)
CertificationUL – Industrial Control Equipment, E65584 CSA – Class 1, Division 2, LR69960C
Bus CommuncationsLocal PCI 2.3 Compliant
LEDs1 Diagnosis/Status Per Channel
Max Modules Per System4
CoatingConformal Coat
Required External PowerNone
Typical AC Signal Delay (Off)29 (+/- 8) ms
Typical DC Signal Delay (Off)30 (+/- 7) ms
UPC10612598117472
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The Allen-Bradley 1785-BCM is a legacy communication module that is used with the PLC5 controller platform. This module is a single-slot chassis that is used to provide communication redundancy and switchover capability from a primary PLC processor to a stand-by PLC5 processor. This module is able to provide high-speed Data Highway Plus (DH+) and Remote I/O (RIO) communication backup via the high-speed serial link (HSSL) with switchover speed up to 1.2 Megabaud.

The 1785-BCM also features an internal buffer amounting up to 4K Words and capable of initiating switchover in different events such as power failure, processor error including 1785-BCM partner module fault. Additionally, switchover may also happen during manual switchover from RUN to PROGRAM mode, REMOTE RUN to REMOTE PROGRAM transition and REM RUN and REMOTE TEST mode changed.

The 1785-BCM is compatible for use with a variety of PLC5 processors such as PLC-5/15 series B, -5/20, -5/25, -5/30, -5/40, and -5/60 processors. It is installed to a 1771 I/O chassis with keying locations between 8 and 10 or between 34 and 36. It requires use of a Wiring Arm with catalog number 1771-WG for fast termination of communication wires to the 1785-BCM.

When using the BCM, input and output modules are not permitted to be installed in the same chassis where the processor and the BCM is installed. The I/O modules must be installed remotely, acting as distributed I/O stations.

Revision Part #Also known as
1785-BCM Ser A1785-BCM/A, Series A, Rev A
1785-BCM Ser B1785-BCM/B, Series B, Rev B
1785-BCM Ser C1785-BCM/C, Series C, Rev C
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